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Berkeley CIVENG 165 - Non-Destructive Methods

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CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionNON-DESTRUCTIVE METHODSNON-DESTRUCTIVE METHODSCE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionNON-DESTRUCTIVE METHODSNON-DESTRUCTIVE METHODSPurpose: quick assessment of the structureCE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionNon-Destructive TechniquesMany industrialized nations currently dedicate a considerable portion of the construction budget for restoration, repair, and maintenance of old structures as opposed to new construction. In 1991 the U.S. Department of Transportation reported that $90.9 billion dollars were required for the rehabilitation and repair of the highway infrastructure system. By 1997, the estimated cost had risen to $212 billion.CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionSURFACE HARDNESS METHODS SURFACE HARDNESS METHODS Essentially, the surface hardness method consists of impacting a concrete surface in a standard manner with a given energy of impact and then measuring the size of indentation or rebound. The most commonly used method employs the Schmidt rebound hammer which consists of a spring-controlled hammer that imparts on a plunger.CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionSchmidt rebound hammer Schmidt rebound hammer Watch the videoCE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionPENETRATION RESISTANCE TECHNIQUESPENETRATION RESISTANCE TECHNIQUESThe equipment used to determine the penetration resistance of concrete consists of a powder-activated device. The Windsor probe uses a powder-activated driver to fire a hardened-alloy probe into the concrete. The exposed length of the probe is a measure of the penetration resistance of concrete. The standard test procedure is described in ASTM C-803.CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionWindsor probeWindsor probeThe type and amount of aggregate play an important role in the penetration resistance, which becomes critical when determining the relationship between penetration resistance and strength. Due to the small volume under testing, the variation in the Windsor probe-test results is higher (as is the case in determining surface hardness) when compared with the variation in standard compressive strength tests on companion specimens. But this method is excellent for measuring the relative rate of strength development of concrete at early ages, especially for determining stripping time for formwork.CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionWindsor probe Windsor probe Watch the videoCompressive strength as a function of exposed probeCE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionPULLOUT TESTS PULLOUT TESTS Schematic diagram of the pullout test Watch the videoCE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionPULLOUT TESTSPULLOUT TESTSA pullout test consists of casting a specially-shaped steel insert with an enlarged end into fresh concrete. This steel insert is then pulled-out from the concrete and the force required for pullout is measured using a dynamometer. A bearing ring is used to confine failure to a well-defined shape.As the steel insert is pulled out, a cone of concrete is also removed, thereby damaging the concrete surface (which must be repaired after the test).CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionMaturity TestsMaturity TestsSince the degree of cement hydration depends on both time and temperature, the strength of concrete may be evaluated from the concept of maturity, which is expressed as a function of the time and the temperature of curing. It is assumed that batches of the same concrete mixtures of same maturity will attain the same strength regardless of the time-temperature combinations leading to that maturity.CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionMATURITY METHOD MATURITY METHOD A simple maturity function M(t) can be defined as the product between time and temperature:() ( )tTTtMoaΔ−=∑or in the limit() ( )dtTTtMt0oa∫−=where ,Δt, Ta , and To are time interval, average concrete temperature during the time interval Dt, and the datum temperature, respectively. Traditionally, -10°C or 14°F isassumed to be the datum temperature below which there is no additional gain in strength.. ASTM C 1074 recommends a datum temperature of 0 °C or 32 °F. When concrete is made with ASTM Type I cement, the datum temperatureis expected to be between 0 and 40 °C (32 and 104 °F)CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionMaturityMaturityInfluence of curing temperature at early ages on the strength-maturity relationship when equation (1) is used with T0 = - 10 °C. This early-age difference can be reduced when better maturity functions are used.CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionABSORPTION AND PERMEABILITY TESTS ABSORPTION AND PERMEABILITY TESTS The rate of water absorption by capillary suction is a good measure of the quality of a concrete and its potential durability when exposed to aggressive environments. Low values of absorption indicate that aggressive ions will have difficulty penetrating the concrete.CE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionInitial Surface AbsorptionTest Initial Surface AbsorptionTest Methods to measure the water absorption under field conditionsCE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionConfiguration of the Figgtest Configuration of the FiggtestCE 165: Concrete Materials and Concrete ConstructionCE 165: Concrete Materials and Concrete ConstructionThe maximum displacement is the amplitude A, the time between two successive wave crests is the period T and the distance between two successive wave crests is the wavelength


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